This invention relates to a speed control mechanism for a rotary dressing wheel which is used on a grinding machine.
U.S. Patent to Stevens, U.S. Pat. No. 3,763,844, recognizes that the speed of traverse of a nonrotating dressing tool along the face of a grinding wheel may be controlled in accordance with wheel diameter. In this patent, as the grinding wheel wears, the rpm of the grinding wheel is increased to maintain constant wheel surface speed. This allows the nonrotating dressing tool to traverse the surface of the grinding wheel in a shorter period of time since the time for one revolution of the grinding wheel at the surface is decreased. A rotary dresser wheel presents a different problem, however. As the cylindrical grinding wheel of a grinding machine becomes worn, its decreasing diameter causes the surface speed of the grinding wheel to decrease. Because this surface speed must be maintained at a certain desired speed, the rpm of the grinding wheel is increased. If the rpm of a dressing wheel is maintained constant, undesirable grinding of a workpiece results as the ratio of the rpm of the grinding wheel to the rpm of the dresser wheel changes.